CHE 107 (Exam 3) – Flashcards

-measured by its tendency to ionize

(more polar = more electronegative)

-the stronger the bond, means the weaker the acid

(harder to breakup, therefore WA)

Includes: F, Cl, Br, I

Strength increases as move down column

F > Cl > Br > I

-Must have: H, O, and Z (central atom)

-=Z - O - H

-Acid strength increases with electronegativity of central atom

-Acid strength increases as oxidation number increases

(more O atoms = more acid strength; draws electron density away from H making it more polar and therefore more electronegative)

-Acid strength increases as move across period

1. Free elements = 0

(H2, Na, Be, K, P4 = 0)

2. Ions = their charge

(Li⁺=+1, Ba²⁺=+2, O^2-=-2)

3. Oxygen is normally -2 in most compounds, but in H₂O₂ and peroxide ion =-1

4. H is +1, except when with metals in binary cmpds, then is -1

(LiH, NaH, CaH₂)

5. F = -1, but all other halides = their charge #

6. Neutral molecule should =0. Charged molecules should add up to their overall charge

(NH₄+ = N(-3) and H₄(+1)

7. Can be integers

(superoxide O₂-=-1/2)

The reaction of an anion or a cation of a salt, or both, with water

-Salts that produce neutral solutions

NaNO₃ --> Na⁺ + NO₃^-

Na+ neither donates or accepts H⁺

No₃^- is CB of SA (HNO₃) and therefore no hydrolysis

-Salts that produce basic solutions

CH₃COONa --> CH₃COO^- + Na⁺

Na⁺ neither donates or accepts H⁺

CH₃COO^- is CB oF WA (CH₃COOH) and therefore wants to gain H⁺, making overall basic

-Salts that produce acidic solutions

NH₄Cl --> NH₄⁺ +Cl^-

Cl^- is CB of SA (HCl) and therefore no hydrolysis

NH₄⁺ is CA of WB (NH₃) and therefore makes acidic---able to donate H⁺ to Cl^-

%H = [C]hydrolyzed at equilibrium  x 100%

[C]initial

Basic: Li, Na, K, Rb, CS, Mg, Ca, Sr, Ba, In, Tl

(all 1A, all 2A except Be, and In₂O₃ & Tl₂O₃)

Acidic: B, C, Si, Ge, N, P, As, Sb, Bi, S, Se, Te, Po, O, Cl, Br, I, At

(all 5A, all 6A except O, all 7A, only B on 3A, top 3 on 4A)

Amphoteric: BeO, Al₂O₃, Ga₂O₃, SnO₂, PbO₂

a substance that can accept a pair of electrons

Ag⁺ + 2NH₃ <---> Ag(NH₃)⁺₂

LA        LB

a substance that can donate a pair of elctrons

Ag⁺ + 2NH₃ <---> Ag(NH₃)⁺₂

LA        LB

an ionic compound formed by the reaction between an acid and a base

-Cation is alkali metal or alkaline earth metal

(ion can neither accept or donate a proton because already has + charge)

-Anion is CB of SA

(CBs of SAs ahve "no appreciable strength")

2 solutes dissolved in a solvent that contain the same ion

HF +H₂O <---> F^- + H3O⁺

NaF ---> Na⁺ + F^-

the shift in equilibrium caused by the addition of a compound having an ion in common with the dissolved substance

*common ion raises pH of acid soln.*

a solution that resists change to pH

(consists of WA or WB and it's conjugate salt)

;

*buffer is a specific type of "common ion effect" problem and therefore H-H equation can be used to calculate pH*

;

;

-Remainder: SA or SB

Procedure: calculate pH directly from molarity of SA or SB

(found in titrations)

;

-Reamainder: WA or WB

Procedure: write substance's equilibrium with water and fill out ICE table

(found in titrations)

(at equivalence point)

-Remainder: CB/CA pair

Procedure: use H-H equation

a substance which changes color with pH

-usually a weak organic acid

-has 2 distinctly different colors in ionized and nonionized form

HIn  + H₂O <---> In^- + H₃O⁺

purple                       red

Q < K_sp

unsaturated

can dissolve more

favors products (shift R more)

Q = Ksp

saturated

equilibrium point ([C]₀ = [C]_e)

Q > Ksp

supersaturated

wants to ppt out more

favors reactant (shift L more)

# mol of solute in 1L of a saturated solution (mol/L)

(s)

Then solubility increases with decreasing pH

(i.e. added acid)

reaction will occur under a certain set of conditions

examples:

-water in a freezer will freeze

-diamonds will convert to graphite (no matter the rate of reaction)

direct measure of randomness or disorder of a system

-larger disorder = larger value of S

-as temperature increases, entropy increases

(molecules morve more rapidly with added heat; entropy of gas is much larger than solid and liquid)

absolute entropy of a substance at 1 atm and 25^o

Celsius

S_solid < S_liquid << S_gas

1. melting

2. vaporization or sublimation

vaporization: liquid --> gas

sublimation: solid --> gas

deposition: gas --> solid

3. dissolving a molecular compound

4. raising the temperature of a system

the entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process

spontaneous:

ΔS_universe = ΔS_system + ΔS_surroundings > 0

*if process has +ΔS_universe, then will be spontaneous)

equilibrium:

ΔS_universe = ΔS_system + ΔS_surroundings = 0

ΔS_surroundings =          1

                                  -ΔH_system

endothermic reaction

-ΔH

+ΔS

exothermic reaction

ΔG = ΔH -TΔS

ΔG < 0: spontaneous

ΔG > 0: spontaneous in reverse direction

ΔG = 0: equilibrium

0= ΔH -TΔS

T = ΔH      

ΔS

the free energy change that occurs when 1 mol of compound is synthesized from its elements in standard states

ΣΔG^o_f(products) and ΣΔG^o_f(reactants)

standard enthalpy of formation of any element in its stable form is 0

ΔG^o_rxn

ΔG^o: ΔG at standard state (only 1 set of conditions)

ΔG: when leaves standard state (ex. at equilibrium)

ΔG = ΔG^o + RTlnQ

when ΔG = 0:

0 = ΔG^o + RTlnK

ΔG^o = -RTlnK

branch of chemistry dealing with interconversion between electrical and chemical energy

-energy is released by spontaneous redox reaction

-energy is used to cause nonspontaneous reaction to occur

experimental apparatus for generating electricity through use of a spontaneous redox reaction

(aka voltaic cell)

amp: # of electrons that move through a wire

cell voltage: "zing" speed on electrons as move through wire (how much force throw ball)

contains an inert (neutral) electrolytic solution that allows the charges on both sides to stay balanced

-electrons leave from L side and as [cation] increases, anions enter to balance

*ALWAYS: anode ---> cathode

the voltage associated with a reduction reaction at an electrode when all solutes are 1M and all gases are 1atm

(E^o_red)

the voltage associated with an oxidation reaction at an electrode when all solutes are 1M and gases are 1atm

(E^o_ox)

sum of standard oxidation potential and standard reduction potential

E^o_cell = E^o_ox + E^o_red

(E^o_cell)

(standard emf)